An upper gastrointestinal series, also called a barium swallow, barium study, or barium meal, is a series of radiographs used to examine the gastrointestinal tract for abnormalities. A contrast medium, usually a radiocontrast agent such as barium sulfate mixed with water, is ingested or instilled into the gastrointestinal tract, and X-rays are used to create radiographs of the regions of interest. The barium enhances the visibility of the relevant parts of the gastrointestinal tract by coating the inside wall of the tract and appearing white on the film. This in combination with other plain radiographs allows for the imaging of parts of the upper gastrointestinal tract such as the pharynx, larynx, esophagus, stomach, and small intestine such that the inside wall lining, size, shape, contour, and patency are visible to the examiner. With fluoroscopy, it is also possible to visualize the functional movement of examined organs such as swallowing, peristalsis, or sphincter closure. Depending on the organs to be examined, barium radiographs can be classified into "barium swallow", "barium meal", "barium follow-through", and "enteroclysis" ("small bowel enema"). To further enhance the quality of images, air or gas is sometimes introduced into the gastrointestinal tract in addition to barium, and this procedure is called double-contrast imaging. In this case the gas is referred to as the negative contrast medium. Traditionally the images produced with barium contrast are made with plain-film radiography, but computed tomography is also used in combination with barium contrast, in which case the procedure is called "CT enterography". The barium swallow, barium meal, and barium follow-through are together also called an upper gastrointestinal series (or study), whereas the barium enema is called a lower gastrointestinal series (or study). In upper gastrointestinal series examinations, the barium sulfate is mixed with water and swallowed orally, whereas in the lower gastrointestinal series (barium enema), the barium contrast agent is administered as an enema through a small tube inserted into the rectum. and esophagus. Although barium X-ray examinations are increasingly being replaced by more modern techniques, such as computer tomography, magnetic resonance imaging, ultrasound imaging, endoscopy and capsule endoscopy, barium contrast imaging remains in common use because it offers the advantages of greater affordability, wider availability, and better resolution in assessing superficial mucosal lesions.
Mechanism
Barium sulfate is swallowed and is a radio opaque substance that does not allow the passage of X-rays. As a result, areas coated by barium sulfate will appear white on an X-ray film. The passage of barium sulfate through the gastrointestinal tract is observed by a radiologist using a fluoroscope attached to a TV monitor. The radiologist takes a series of individual X-ray images at timed intervals depending on the areas to be studied. Sometimes medication which produces gas in the gastrointestinal tract is administered together with the Barium sulfate. This gas distends the gastrointestinal lumen, providing better imaging conditions and in this case the procedure is called double-contrast imaging.
Procedure
Clinical status and relevant medical history are reviewed prior to the studies.
Amongst the uses of barium swallow are: persistent dysphagia and odynophagia despite negative esophagogastroduodenoscopy (OGDS) findings, failed OGDS, esophageal motility disorder, globus pharyngeus, assessment of tracheoesophageal fistula, and timed barium swallow to monitor the progress of esophageal achalasia therapy. Barium sulfate suspension such as 100 ml or more of E-Z HD 200 to 250% concentration and Baritop 100% can be used. Water-soluble contrast agent such as Gastrografin (diatrizoate) and Conray (Iotalamic acid) is used instead of barium if oesophageal perforation is suspected. Low osmolar contrast medium with concentration of 300 mg/ml is used instead of gastrografin if there is risk of aspiration or there is tracheoesophageal fistula. Normally, 90% of ingested fluid should have passed into the stomach after 15 seconds.
Right anterior oblique (RAO) view is to see the oesophagus clearly, away from overlapping spine.
Barium is administered orally, sometimes mixed with diatrizoic acid (gastrografin) to reduce transit time in the bowel. Intravenous metoclopramide is sometimes also added to the mixture to enhance gastric emptying. Other methods to reduce transit time are to add ice cold normal saline after the administration of barium saline mixture or to give a dry meal.
X-ray images are then taken in a supine position at intervals of 20–30 minutes. Real-time fluoroscopy is used to assess bowel motility. The radiologist may press or palpate the abdomen during images to separate intestinal loops. The total time necessary for the test depends on the speed of bowel motility or transit time and may vary between 1 and 3 hours.
Enteroclysis
Enteroclysis is also known as small bowel enema. It has been largely replaced by magnetic resonance enterography/enteroclysis
In addition to fasting for 8 hours prior to examination, a laxative may also be necessary for bowel preparation and cleansing.
Interpretation of results
thumbnail|[[Zenker's diverticulum as seen in a barium swallow examination]]
- Enteroclysis has shown to be very accurate in diagnosing small bowel diseases, with a sensitivity of 93.1% and specificity of 96.9%. It permits detection of lesion which may not be seen with other imaging techniques.
- The interpretation of standard barium swallow examinations for assessing dysphagia is operator and interpreter dependent. It has poor sensitivity for subtle abnormalities but is more sensitive in detecting esophageal webs and rings than gastroscopy. Barium swallow studies remain the main investigation of dysphagia. Barium studies may detect pharyngeal tumors that are difficult to visualize endoscopically.
- Barium follow-through examinations are the most commonly used imaging technique in assessing patients with Crohn's disease, although CT and magnetic resonance imaging are widely accepted as being superior. Radiographic imaging in Crohn's disease provides clinicians with objective evaluations of small bowel regions that are not accessible to standard endoscopic techniques. Because of its length and complex loops, the small intestine is the most difficult part of the gastrointestinal tract to evaluate. Most endoscopic techniques are limited to the examination of proximal or distal segments, hence Barium follow-through remains in most centres the test of choice for the investigation of abdominal pain, diarrhoea and in particular diseases manifesting mucosal abnormalities such as coeliac and Crohn's disease.
- Barium fluoroscopic examinations have some advantages over computed tomography and magnetic resonance techniques, such as higher spatial resolution and the ability to examine bowel peristalsis and distension in real time.
- Many infections and parasitic infestations produce patterns of the luminal surface, which are best seen on Barium examinations. Certain parasites are seen as filling defects outlined by Barium and Barium examinations play an important role in the diagnosis of intestinal infections and infestations as compared to other techniques. Barium studies show tapeworms and roundworms as thin, linear filling defects of the bowel. Because roundworms have a developed alimentary tract, barium may outline the parasites' intestinal tracts on delayed images. In Strongyloidiasis barium studies show intestinal wall oedema, thickening of intestinal folds with flattening, and atrophy of the overlying mucosa.
Adverse effects
thumbnail|Barium in the lungs resulting from aspiration during a barium swallow
- Radiographic examinations involve radiation exposure in the form of X-rays.
- Constipation and abdominal pain may occur after barium meals.